KR20140134303A - Conductive paste and die bonding method - Google Patents

Abstract

By using silver particles having a predetermined crystal change characteristic defined by XRD analysis, it is possible to easily control the sinterability of the silver particles in the conductive paste, and furthermore to provide excellent electrical conductivity and thermal conductivity after the sintering treatment, A conductive paste which can be stably obtained and a die bonding method using the same are provided. A silver paste having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material and a conductive paste containing a dispersion medium for forming a paste, The peak integral intensity at 38 ° ± 0.2 ° is represented by S1 and the peak integral intensity at 2θ = 38 ° ± 0.2 ° in the X-ray diffraction chart obtained by XRD analysis after the sintering treatment (250 ° C., 60 minutes) When the integral intensity is S2, the value of S2 / S1 is set to a value within the range of 0.2 to 0.8.

Description

[0001] CONDUCTIVE PASTE AND DIE BONDING METHOD [0002]

The present invention relates to a conductive paste and a die bonding method.

Particularly, by using silver particles having a predetermined crystal change characteristic defined by XRD analysis, it is possible to easily control the sinterability of the silver particles, and furthermore, after the sintering treatment, excellent electrical conductivity and thermal conductivity can be stably And a die bonding method using the conductive paste.

BACKGROUND ART [0002] Various conductive paste for die bonding comprising silver particles and a die bonding method of a semiconductor element using such conductive paste have been proposed.

For example, there has been proposed a paste composition for bonding a metal-based adherend which is sintered by heating to obtain a solid silver having excellent strength, electrical conductivity and thermal conductivity (see Patent Document 1).

More specifically, (A) spherical particles made of a reducing method having an average particle diameter of 0.1 to 6 탆 and a carbon content of 0.50% by weight or less, (B) water having a boiling point of 70 to 250 캜, water, a volatile monohydric alcohol, Wherein the volatile dispersant is volatile by heating at a temperature of 100 ° C or more and 250 ° C or less, and the spherical silver particles are dispersed in the volatile silicone oil, Is sintered to have a volume resistivity of 1 x 10 < ^-4 > [Omega] -cm or less and a solid shape having a thermal conductivity of 5 W / mK or more, is a composition for bonding between adherends of metal .

Further, there has been proposed a method of controlling the sintering property of silver particles to form a sintered product with a small amount of cracks, thereby firmly adhering the adherends of the metal system (see Patent Document 2).

More specifically, a paste-like metal particle composition comprising (A) heat-sinterable metal particles having an average particle diameter of more than 0.1 μm and not more than 50 μm and (B) a volatile dispersion medium is interposed between a plurality of metal members, (B) in an amount of not less than 10% by weight and not more than 100% by weight of the volatile dispersion medium (B) in the paste-like metal particle composition by heating at a temperature of not less than 200 占 폚 and not more than 200 占 폚, (B) remaining in the paste-like metal particle composition is sintered by heating at a temperature of not higher than 50 DEG C and sintering the heat-sinterable metal particles (A) to bond the plurality of metal members together To the metal member.

In addition, a paste-form silver nanoparticle composition in which the effects of high-grade fatty acids or the like covering the surface of the heat-sinterable metal particles are eliminated and the silver particles are easily sintered by heating to form a solid silver having excellent strength, electrical conductivity and thermal conductivity (See Patent Document 3).

More specifically, it comprises (A) a silver particle whose surface is coated with a high or intermediate fatty acid (b1) or a derivative (b2) of a high or intermediate fatty acid (b1) and (B) a volatile dispersion medium, In the paste composition in which the volatile dispersion medium is volatilized and the silver particles are sintered together, the high- or intermediate-level fatty acid (b1) covering the silver particle surface or the derivative (b2) of the high- (A1) or a derivative (a2) of a higher fatty acid (a1) which has been coated with the particle surface in advance is mixed with a higher or intermediate fatty acid (b1) lower in the higher fatty acid (a1) And the derivative (b2).

Further, flattened silver particles which can obtain a conductor film with a low resistance (low resistance) by increasing the orientation of particles when a conductor film is formed have been proposed (see Patent Document 4).

More specifically, the flatness particle is characterized in that the ratio P ₂₀₀ / P ₁₁₁ of the peak P ₂₀₀ of the (200) plane to the peak P ₁₁₁ of the (111) plane obtained by XRD measurement is 0.3 or less.

Japanese Patent No. 4347381 (claims and the like) Japanese Patent Application Publication No. 2010-53377 (claims) Japanese Patent Application Publication No. 2009-289745 (claims) Japanese Patent Application No. 2012-36481 (claims)

However, since the compositions and the like disclosed in Patent Documents 1 to 4 do not take into account the crystal change characteristics before and after the sintering treatment of the metal particles as the sinterable conductive material, the paste phase is a metal The sintering property of the particles can not be stably controlled.

Namely, due to various factors such as the production method and the like, the metal particles vary in crystal change characteristics when the sintering treatment is performed, and therefore, as in Patent Documents 1 to 4, the state of the metal particles before sintering Even if the sintering treatment conditions are controlled, the sintering property can not be controlled depending on the kind of the metal particles, and the desired electrical conductivity and thermal conductivity can not be stably obtained.

In addition, in the paste composition for bonding a metallic adherend disclosed in Patent Document 1, it is required that the composition should strictly control the carbon content derived from the coating material covering the particles to 0.50 wt% or less I saw a problem.

Although it has been disclosed that such a carbon content is controlled by washing the particles in the spherical shape, it is difficult to uniformly control the coating material so that it can not be managed quantitatively. As a result, the sinterability of the silver particles can be stably controlled I could not do it.

In the paste phase disclosed in Patent Document 2, metal particles (such as silver particles or copper particles) to be used in a composition or the like are heated in an inert gas at a predetermined temperature (40 to 200 캜) to form a volatile dispersion medium There is a manufacturing problem that a heat treatment must be performed at a predetermined temperature (70 to 400 占 폚) in an oxidizing gas or a reducing gas.

In addition, since it is difficult to uniformly volatilize the volatile dispersion medium in an inert gas, it can not be controlled quantitatively. As a result, there has been a problem that the sinterability of metal particles can not be stably controlled yet.

The paste phase disclosed in Patent Document 3 has a manufacturing problem in that it has to be replaced by a higher / intermediate fatty acid, which is lower in level than that of a higher / intermediate fatty acid covering the surface of silver particles to be used .

As a substitution method, it has been disclosed that silver particles coated with a high / medium fatty acid or the like are immersed in a lower / higher fatty acid having a lower degree. However, since it is difficult to uniformly substitute silver particles, they can not be managed quantitatively. There is a problem that the sinterability of the silver particles can not be stably controlled yet.

In addition, in the case of a flat-particle-containing paste-like composition disclosed in Patent Document 4, in the case of a composition or the like, a predetermined flattened silver is produced in a state in which an aqueous solution containing a water-soluble silver compound coexists with carboxylic acids, amines or thiols , There has been a manufacturing problem that a reducing agent must be added sequentially to an aqueous solution heated to 60 ° C or higher.

The present inventors have intensively studied and, as a result, have found that, by using silver particles of a predetermined particle size having a predetermined crystal change characteristic specified by XRD analysis as a sinterable conductive material and by containing a dispersion medium for forming a paste, The sinterability of the sintered body can be easily controlled, and the present invention has been completed.

That is to say, the present invention provides a method for producing a sintered body, which can easily control the sinterability of silver particles without depending on the crystallinity of the silver particles before the sintering treatment, and furthermore, after the sintering treatment, Paste and a die bonding method using the same.

The above-mentioned "crystallinity of silver particles before sintering" means the integral strength, peak height, half width, etc. of each peak in the X-ray diffraction chart of silver particles before sintering treatment.

According to the present invention, there is provided an electroconductive paste containing silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material and a dispersion medium for forming a paste, and an X-ray diffraction chart Of the peak of 2? = 38 占 占 占 at 2? = 38 占 in the X-ray diffraction chart obtained by XRD analysis after sintering treatment of silver particles (250 占 폚, 60 minutes) And a value of S2 / S1 is set to a value within a range of 0.2 to 0.8 when the integral intensity of a peak of 占 0.2 占 is taken as S2. Thus, the above-described problem can be solved.

That is, according to the conductive paste of the present invention, as the sinterable conductive material, by using the silver particles having the predetermined crystal size and having the predetermined crystal change characteristics defined by the XRD analysis, the conductive paste The sinterability of the silver particles in the sintered body can be easily controlled and, furthermore, after the sintering treatment, excellent electrical conductivity and thermal conductivity can be stably obtained.

In constructing the conductive paste of the present invention, the peak height of the peak at 2θ = 38 ° ± 0.2 ° in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of silver particles is defined as L1, When the peak height of the peak at 2? = 38 占 0.2 占 in the X-ray diffraction chart obtained by XRD analysis after sintering (250 占 폚 for 60 minutes) is L2, the value of L2 / L1 is set to 0.5 to 1.5 It is preferable to set the value within the range.

By such a constitution, the crystal change characteristics of the silver particles become more favorable, and the sinterability of the silver particles in the conductive paste can be more easily controlled.

In constructing the conductive paste of the present invention, the half width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is W1, The value of W2 / W1 is set to 0.3 to 0.9 when the half-width of the peak at 2 [theta] = 38 [deg.] +/- 0.2 [deg.] In the X-ray diffraction chart obtained by XRD analysis after sintering (250 DEG C, Is preferably within a range of "

By such a constitution, the crystal change characteristics of the silver particles become more favorable, and the sinterability of the silver particles in the conductive paste can be controlled more easily.

In forming the conductive paste of the present invention, it is preferable that silver particles are hollow particles.

By such a constitution, the sinterability of the silver particles in the conductive paste can be controlled more easily, and the weight of the conductive paste can be reduced and the cost can be reduced.

In forming the conductive paste of the present invention, it is preferable that the surface of silver particles is covered with an organic surface treatment agent comprising at least one selected from organic acids, organic acid salts, surfactants and coupling agents.

By such a constitution, the crystal change characteristics of the silver particles can be controlled, and further, the sinterability of the silver particles in the conductive paste can be controlled more easily.

In forming the conductive paste of the present invention, it is preferable that the mixing amount of the dispersion medium is within a range of 5 to 30 parts by weight based on 100 parts by weight of silver particles.

By such a constitution, an appropriate viscosity can be given to the conductive paste while stably maintaining the sinterability of the silver particles in the conductive paste.

In forming the conductive paste of the present invention, it is preferable that the dispersion medium is at least one compound selected from the group consisting of a glycol ether compound, a glycol ester compound, a hydrocarbon compound and a polar solvent.

By such a constitution, an appropriate viscosity can be given to the conductive paste while maintaining the sinterability of the silver particles in the conductive paste more stably.

Further, in forming the conductive paste of the present invention, it is preferable to further contain an organic compound and make the amount of the organic compound to fall within a range of 0.5 to 10 parts by weight based on 100 parts by weight of the silver particles.

By such a constitution, it is possible to improve the stability over time of the sintered silver particles while stably maintaining the sinterability of the silver particles in the conductive paste.

In forming the conductive paste of the present invention, it is preferable that the organic compound is a thermosetting resin containing at least one of an epoxy resin and a phenol resin.

By such a constitution, the stability with time of the sintered silver particles can be improved while maintaining the sinterability of the silver particles in the conductive paste more stably.

In another aspect of the present invention, there is provided a sinterable electroconductive material comprising silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material, a dispersion medium for forming a paste, and X Ray diffraction chart obtained by XRD analysis after sintering treatment of silver particles (250 占 폚, 60 minutes) with S1 as the integrated intensity of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart = 38 deg. 0.2 deg. Is S2, the conductive paste having the value of S2 / S1 within the range of 0.2 to 0.8 is applied to a predetermined position on the substrate for mounting the semiconductor element And a step of sintering the silver particles by heating at a temperature of 200 to 450 占 폚 to mount the semiconductor element on the substrate.

That is, according to the die bonding method of the present invention, since a predetermined conductive paste is used, the semiconductor device can be stably mounted on a substrate in a state of exhibiting excellent electrical conductivity and thermal conductivity.

1 (a) and 1 (b) are XRD spectrum charts of silver particles in Example 1. Fig.
Fig. 2 is a view for explaining the relationship between the integral intensity ratio of peaks at 2 &thetas; = 38 DEG +/- 0.2 DEG before and after the sintering treatment and the resistivity. Fig.
Fig. 3 is a view for explaining the relationship between the peak height ratio of peaks at 2? = 38 占 짹 0.2 占 before and after the sintering treatment and the resistivity. Fig.
Fig. 4 is a view for explaining the relationship between the half-width ratio of the peak at 2? = 38 占 짹 0.2 占 before and after the sintering treatment and the resistivity. Fig.
Fig. 5 is a view for explaining the relationship between the compounding of an organic compound and the durability of heat conduction. Fig.
6 is a view for explaining the relationship between the compounding of the organic compound and the resistivity.
7 (a) to (b) are XRD spectrum charts of silver particles in Example 2. Fig.
8 (a) - (b) are XRD spectrum charts of silver particles in Example 3. Fig.
9 (a) and 9 (b) are XRD spectrum charts of silver particles in Example 4. Fig.
10 (a) to (b) are XRD spectrum charts of silver particles in Example 5. Fig.
11 (a) and (b) are XRD spectrum charts of silver particles in Example 6. Fig.
12 (a) to 12 (b) are XRD spectrum charts of silver particles in Example 7. Fig.
13 (a) and 13 (b) are XRD spectrum charts of silver particles in Example 8. Fig.
14 (a) and 14 (b) are XRD spectrum charts of silver particles in Example 9. Fig.
15 (a) to 15 (b) are XRD spectrum charts of silver particles in Example 10. Fig.
16 (a) and 16 (b) are XRD spectrum charts of silver particles in Example 11. Fig.
17 (a) to (b) are XRD spectrum charts of silver particles in Comparative Example 1. Fig.
18 (a) to 18 (b) are XRD spectrum charts of silver particles in Comparative Example 2. Fig.
19 (a) to (b) are XRD spectrum charts of silver particles in Comparative Example 3. Fig.
20 (a) to 20 (b) are XRD spectrum charts of silver particles in Comparative Example 4. Fig.

[First Embodiment]

The first embodiment is an electroconductive paste containing silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material and a dispersion medium for forming a paste, The total intensity of 2? = 38 in the X-ray diffraction chart obtained by XRD analysis after the sintering treatment (250 占 폚, 60 minutes) of silver particles and the integral intensity of the peak at 2? = 38? And a value of S2 / S1 is set to a value within a range of 0.2 to 0.8 when the integral intensity of the peak of 占 0.2 占 is S2.

Hereinafter, the conductive paste of the first embodiment will be described specifically for each constituent requirement.

1. Silver particles

(1) Volume average particle diameter

And the volume average particle diameter of the silver particles as the sinterable conductive material is set to a value within a range of 0.1 to 30 mu m.

The reason for this is that when the volume average particle diameter of the silver particles is less than 0.1 탆, the silver particles tend to agglomerate and the handling property may be excessively lowered. On the other hand, when the volume average particle diameter of the silver particles exceeds 30 탆, the sinterability may remarkably decrease or the paste may become difficult to form.

Therefore, the volume average particle diameter of the silver particles is more preferably in the range of 0.5 to 15 占 퐉, and more preferably in the range of 1.5 to 5 占 퐉.

The volume average particle diameter of the silver particles can be measured by a laser diffraction / scattering method particle size distribution measuring apparatus, or can be measured from an electron microscope photograph or from an electron microscope photograph using the image processing apparatus You may.

(2) Type

The shape of the silver particles is not particularly limited, and may be spherical, elliptic spherical, cubic, rod-like, chestnut-like, flaky, dissimilar, or a combination thereof.

Further, with respect to the shape of the silver particles, it is more preferable that the hollow particles having a predetermined void space therein are particles.

The reason for this is that by using such hollow particles, sintering of the silver particles in the conductive paste can be more easily controlled, and the weight of the conductive paste can be reduced and the cost can be reduced.

(3) Bulk density

It is also preferable that the bulk density of the silver particles be in the range of 0.5 to 8 g / cm 3.

The reason is that when the bulk density of the silver particles is less than 0.5 g / cm 3, the tensile strength of the conductive paste after sintering lowers and cracks tend to occur. On the other hand, if the bulk density of the silver particles exceeds 8 g / cm 3, it may become difficult to stably control the sinterability in the conductive paste.

Therefore, the bulk density of the silver particles is more preferably in the range of 2 to 7 g / cm 3, more preferably in the range of 4 to 6 g / cm 3.

The bulk density of such silver particles can be measured in accordance with the JIS K5101 tap method.

(4) Surface covering

It is also preferable that the surface of the silver particles is covered with an organic surface treatment agent comprising at least one selected from an organic acid, an organic acid salt, a surfactant and a coupling agent.

The reason for this is that by coating the surface of the silver particles with such an organic surface treatment agent, the crystal change characteristics of the silver particles can be controlled, and furthermore, the sinterability of the silver particles in the conductive paste can be controlled more easily to be.

(4) -1 type

Examples of the organic surface treatment agent include, but are not limited to, hexanoic acid, 2-ethylhexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, Hydroxystearic acid, benzoic acid, gluconic acid, cinnamic acid, salicylic acid, gallic acid, pentadecanoic acid, heptadecanoic acid, arachic acid, lignoceric acid, heptanoic acid, 2- Specific examples include monobasic acids such as pentynonanoic acid, 2-hexyldecanoic acid, 2-heptyldodecanoic acid, isostearic acid, palmitoleic acid, isooleic acid, elaidic acid, ricinoleic acid, valoleic acid, erucic acid, mountain; And dibasic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, malic acid, phthalic acid and fumaric acid may be used singly or in combination.

(4) -2 Amount

The blending amount of the organic surface treatment agent is preferably set to a value within a range of 0.1 to 3 parts by weight with respect to 100 parts by weight of silver particles.

The reason for this is that by adjusting the compounding amount of the organic surface treatment agent, the crystal change characteristics of the silver particles can be controlled, and further, the sinterability of the silver particles in the conductive paste can be controlled more easily.

That is, when the blending amount of the organic surface treatment agent is less than 0.1 part by weight, the silver particles tend to agglomerate easily. On the other hand, when the blending amount of the organic surface treatment agent exceeds 3 parts by weight, good sinterability may not be obtained.

Therefore, the blending amount of the organic surface treating agent is more preferably in a range of 0.5 to 2.5 parts by weight, and more preferably in a range of 1 to 2 parts by weight, based on 100 parts by weight of silver particles.

(4) -3 carbon amount

Further, it is preferable that the carbon content with respect to the whole silver particles (100% by weight) is within a range of 0.05 to 3% by weight.

The reason for this is that when the carbon content is less than 0.05% by weight, the silver particles tend to agglomerate easily. On the other hand, if the carbon content exceeds 3% by weight, good sinterability may not be obtained.

Accordingly, the carbon content with respect to the silver particles (100 wt%) is more preferably in the range of 0.1 to 2 wt%, and still more preferably in the range of 0.55 to 1 wt%.

(5) XRD analysis

(5) -1 integral intensity ratio

When the integrated intensity of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is represented by S1, the sintering treatment of silver particles (250 占 폚, 60 minutes) , The value of S2 / S1 is set to a value within the range of 0.2 to 0.8, where S2 is the integral intensity of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis of .

The reason for this is that by using the silver particles having such predetermined crystal change characteristics, it is possible to easily control the sinterability of the silver particles in the conductive paste without depending on the crystallinity of the silver particles before the sintering treatment, and furthermore, This is because excellent electrical conductivity and thermal conductivity can be stably obtained later.

That is, when the integral intensity ratio is less than 0.2, the durability thermal conductivity after the sintering treatment may be excessively lowered. On the other hand, when the integral intensity ratio exceeds 0.8, the electrical conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase.

Therefore, after the sintering treatment (at 250 DEG C for 60 minutes) of the silver particles, the integrated intensity of the peak at 2? = 38 DEG +/- 0.2 DEG in the X-ray diffraction chart obtained by the XRD analysis before the sintering treatment of the silver particles was S1, , The value of S2 / S1 is preferably set to a value within a range of 0.25 to 0.75 when the integral intensity of a peak at 2? = 38 占 占 占 is 2 in the X-ray diffraction chart obtained by XRD analysis of , And more preferably in the range of 0.3 to 0.7.

In the present invention, the sintering treatment for performing the XRD analysis of the silver particles after the sintering treatment means that silver particles in a state of not containing an additive such as a dispersion medium are coated on a glass plate surface in a thickness of 100 mesh And sintered by heating in a circulating air dryer under the condition of 250 캜 for 60 minutes.

Therefore, in the sintering treatment for performing the XRD analysis of the silver particles after the sintering treatment, since each silver particle remains in a particulate state even after the sintering treatment, it can be accommodated in the cell and subjected to XRD analysis.

On the other hand, when the conductive paste is sintered, it means that the silver particles in the conductive paste are mutually melted and partially connected to each other.

Here, the outline of the relationship between the X-ray diffraction chart obtained by the XRD analysis before the sintering treatment of silver particles and the crystal characteristics thereof will be described.

That is, Fig. 1 (a) shows an XRD spectrum chart before sintering treatment of silver particles in Example 1 of the present invention, and Fig. 1 (b) An XRD spectrum chart after the sintering treatment of the particles is shown.

As can be understood from the XRD spectrum charts of Figs. 1 (a) to 1 (b), metal silver usually has a diffraction peak of 2θ = 38 ° ± 0.2 ° and a (111) The diffraction peaks of the (200) plane were measured at 2θ = 64 ° ± 0.2 ° and the diffraction peaks of the (220) plane were measured at 2θ = 77 ° ± 0.2 ° and the diffraction peaks of the (311) Deg.] And (222) planes, respectively.

It has been confirmed by the present inventors that these peaks vary in various ways as the crystal characteristics of the silver particles are changed by sintering treatment.

In addition, the characteristic of the crystal change due to the sintering treatment, that is, the crystal change characteristic, is not determined uniquely according to the XRD spectrum of the silver particle before the sintering treatment and the sintering treatment conditions, .

More specifically, even if the XRD spectrum of the silver particles before the sintering treatment and the sintering treatment conditions are the same, the crystal characteristics of the silver particles after the sintering treatment largely differ depending on the crystal change characteristics potentially possessed by the silver particles .

Among the various crystal change characteristics, the integral intensity ratio S2 / S1 of the peak at 2? = 38 占 占 占 has a clear correlation between the electric conductivity and the thermal conductivity in the conductive paste after the sintering treatment, It is confirmed that the electrical conductivity and thermal conductivity of the conductive paste after the sintering treatment can be stably controlled, thereby completing the present invention.

That is, a peak of 2? = 38 ° ± 0.2 °, 2θ = 44 ° ± 0.2 °, 2θ = 64 ° ± 0.2 °, 2θ = 77 ° ± 0.2 ° and 2θ = 81 ° ± 0.2 ° (Ω · cm) in the conductive paste after the sintering treatment, but the integral intensity ratio (-) of the peak intensity of the peak of 2θ = 38 ° ± 0.2 ° Are correlated with each other.

More specifically, the coefficient of determination R ² between the integral intensity ratio (-) in the case of 2? = 38 占 占 占 and the resistivity (? 占 에) in the conductive paste after the sintering treatment is 0.84 Which is a very high value.

On the other hand, 2θ = 44 ° R ² in the case of ± 0.2 ° is 0.79, 2θ = 64 ° ± R 2 in R ² of 0.2 ° if in the case of 0.80, 2θ = 77 ° ± 0.2 ° is 0.68, 2θ = 81 R ² in the case of ± 0.2 ° is 0.46, and it is confirmed that the value of the coefficient of determination is smaller than that in the case of 2θ = 38 ° ± 0.2 °.

The coefficient of determination R ² is a coefficient used as a scale for seeing the degree of accuracy (accuracy) of the regression equation (approximate expression), which is the square of the correlation coefficient R.

The reason why the integrated intensity ratio of peaks such as 2? = 38 占 占 占 is a clear correlation between the electric conductivity and the thermal conductivity in the conductive paste after sintering is not clear at this point, It is presumed that the elapsed time of the change due to the sintering process, such as the crystallite size and the distribution of the crystalline phase, constituting the sintering process greatly affects the conductivity of the silver particles after the sintering process.

Next, with reference to Fig. 2, the relationship between the integral intensity ratio of peak at 2θ = 38 ° ± 0.2 ° before and after the sintering treatment and the specific resistance will be described.

That is, in Fig. 2, the integral intensity ratio S2 / S1 (-) of the peak at 2 [theta] = 38 [deg.] +/- 0.2 [deg.] Before and after the sintering treatment for the silver particles is taken on the abscissa, And a characteristic curve showing a specific resistance (? 占) m) is shown.

From this characteristic curve, it is possible to read the correlation between the positive values that the resistivity increases with the increase of the integral intensity ratio.

In a more specific, the integrated intensity ratio of 0.2 point, the specific resistance is about 2 × 10 ^-6 Ω · ㎝ a low value, the point in the integrated intensity ratio is 0.8, the resistivity of about 2 × 10 ^-5 Ω · ㎝, And maintains a level of electrical conductivity practically unproblematic.

On the other hand, when the integral intensity ratio exceeds 0.8, the resistivity increases as it is. For example, when the integral intensity ratio is 0.9, it becomes a very large value of about 1 x ^10-4 ? It can be seen that the electric conductivity of the level can not be obtained.

Therefore, it is understood from the characteristic curve shown in Fig. 2 that the predetermined electric conductivity can be stably obtained by setting the predetermined integral intensity ratio within the range of 0.2 to 0.8.

(5) -2 Peak height ratio

The peak height of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is represented by L1, and the peak height after sintering (250 占 폚, 60 minutes) It is preferable that the value of L2 / L1 is set to a value within the range of 0.5 to 1.5 when the peak height of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by the XRD analysis is L2.

The reason for this is that by further limiting the crystal change characteristic defined by the integral intensity ratio by the peak height ratio, the crystal change characteristics of the silver particles become more favorable and the sinterability of the silver particles in the conductive paste can be controlled more easily It is because.

That is, when the peak height ratio is less than 0.5, the durability thermal conductivity after the sintering treatment may be excessively lowered.

On the other hand, when the peak height ratio exceeds 1.5, the electrical conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase.

Therefore, when the peak height of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is represented by L1 and the peak height after the sintering (250 占 폚, 60 minutes) It is more preferable to set the value of L2 / L1 within the range of 0.6 to 1.4 when the peak height of 2? = 38 占 占 占 is L2 in the X-ray diffraction chart obtained by XRD analysis, It is more preferable to set the value of L1 to a value within the range of 0.7 to 1.2.

Next, with reference to Fig. 3, the relationship between the peak height ratio of the peak at 2 [theta] = 38 [deg.] +/- 0.2 [deg.] Before and after the sintering treatment and the specific resistance will be described.

3, the axis of abscissas represents the peak height ratio L2 / L1 (-) of the peak at 2θ = 38 ° ± 0.2 ° before and after the sintering treatment, and the ordinate represents the resistivity (Ω · cm) of the conductive paste after the sintering treatment The characteristic curve is shown.

From this characteristic curve, it is possible to read the correlation between the positive values that the resistivity increases as the peak height ratio increases.

More specifically, at a peak height ratio of 0.5, the resistivity is as low as about 4 × 10 ^-6 Ω · cm, and even when the peak height ratio is 1.5, the resistivity is about 1 × 10 ^-5 Ω · cm, And maintains a level of electrical conductivity of no problem.

On the other hand, when the peak height ratio exceeds 1.5, the resistivity increases as it is, and it is sometimes difficult to stably obtain the electric conductivity of a practically required level.

Therefore, it is understood from the characteristic curve shown in Fig. 3 that the prescribed electric conductivity can be stably obtained by setting the predetermined peak height ratio within the range of 0.5 to 1.5.

(5) -3 half width ratio

Further, when the half-value width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is W1, the sintering treatment (250 占 폚, 60 minutes) W2 is a value within a range of 0.3 to 0.9, where W2 is a half-value width of a peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis of?

This is because the crystal change characteristics of the silver particles become more favorable by further limiting the crystal change characteristic defined by the integral intensity ratio by the half value ratio so that the sinterability of the silver particles in the conductive paste can be controlled more easily It is because.

That is, when the half-width ratio is less than 0.3, the electrical conductivity after sintering decreases and the specific resistance may increase excessively. On the other hand, even when the half width ratio becomes a value exceeding 0.9, the electrical conductivity after the sintering process deteriorates and the specific resistance may excessively increase.

Therefore, assuming that the half-width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before sintering the silver particles is W1, It is more preferable to set the value of W2 / W1 to a value within the range of 0.2 to 0.8, where W2 is the half width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis, And more preferably in the range of 0.4 to 0.7.

Next, with reference to Fig. 4, the relationship between the half width ratio of the peak at 2 &thetas; = 38 DEG +/- 0.2 DEG before and after the sintering treatment and the resistivity will be described.

That is, in FIG. 4, the abscissa represents the half-width ratio W2 / W1 (-) of the peak at 2? = 38 占 0.2 占 before and after the sintering treatment and the ordinate represents the resistivity (? The characteristic curve is shown.

From this characteristic curve, it is possible to read the correlation between the positive values that the resistivity is decreased once by taking the minimum value, and then increased as the half width ratio is increased.

More specifically, for example, when the half width ratio is 0.2, the resistivity becomes a very large value of about 1 x 10 < ^-4 > [Omega] -cm and it can be seen that the electric conductivity of a practically required level can not be obtained .

On the other hand, when the half width ratio is 0.3 or more, the resistivity shows a level of practically no problem at about 1 x 10 < ^-5 > × 10 ^-6 Ω · cm), and when the half width ratio exceeds 0.9, the specific resistance increases again to a value exceeding about 1 × 10 ^-5 Ω · cm, and it is understood that the resistivity deteriorates.

Therefore, it is understood from the characteristic curve shown in Fig. 4 that the predetermined electric conductivity can be stably obtained by setting the predetermined half width ratio to a value within the range of 0.3 to 0.9.

(5) -4 initial crystallization property

Further, the present invention is characterized in that the crystal change characteristics in silver particles before and after the sintering treatment are defined, but preferable ones are shown below as the crystal characteristics in the silver particles before the sintering treatment, that is, the initial crystal properties.

That is, it is preferable that the integral intensity of the peak of 2? = 38 占 占 占 at the silver particle before the sintering treatment is within the range of 4500 to 7500 cps 占.

This is because if the integral strength is less than 4500 cps · °, the electrical conductivity after the sintering treatment is lowered and the specific resistance may excessively increase. On the other hand, if the integral strength is higher than 7500 cps · °, the durability of the durability thermal conductivity after sintering may be excessively lowered.

Therefore, it is more preferable to set the integrated intensity of the peak of 2? = 38 占 占 占 at the silver particle before the sintering treatment to a value within the range of 5,000 to 7,000 cps 占, and a value within the range of 5500 to 6500 cps 占Is more preferable.

Further, it is preferable that the peak height of the peak of 2? = 38 占 占 占 at the silver particle before the sintering treatment is within the range of 6000 to 38000 cps.

The reason for this is that when the peak height is less than 6000 cps, the electrical conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase. On the other hand, if the peak height exceeds 38000 cps, the durability thermal conductivity after the sintering treatment may be excessively lowered.

Therefore, it is more preferable that the peak height of the peak of 2? = 38 占 占 占 at the silver particle before the sintering treatment is more preferably in the range of 8000 to 35000 cps, more preferably in the range of 10000 to 32000 cps .

Further, when the sintering treatment before the 2θ = 38 ° ± 0.2 ° peak heights of the peaks for L1 _38, 2θ = 44 ° ± peak height of the 0.2 ° peak in the particle to the L1 _44, L1 ₄₄ / L1 ₃₈ Is preferably set to a value within a range of more than 0.2 and not more than 0.5.

This is because if the peak height ratio is less than 0.2, the electrical conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase. On the other hand, even when the peak height ratio exceeds 0.5, the electrical conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase.

Thus, prior to the sintering process it is when the 2θ = 38 ° ± 0.2 ° peak heights of the peaks for L1 _38, 2θ = 44 ° ± peak height of the 0.2 ° peak in the particle to the L1 _44, L1 ₄₄ / L1 ₃₈ Is more preferably set in a range of more than 0.3 and not more than 0.4.

2. Distribution

(1) Type

The kind of the dispersion medium for forming the paste is not particularly limited, but is preferably at least one compound selected from the group consisting of glycol ether compounds, glycol ester compounds, hydrocarbon compounds and polar solvents.

This is because such a dispersion medium can impart an appropriate viscosity to the conductive paste while maintaining the sinterability of the silver particles in the conductive paste more stably.

First, as the glycol ether compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether , Ethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, Diethylene glycol monomethyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether Propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, Propylene glycol monohexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoisopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monobutyl ether, Glycol monoisobutyl ether, dipropylene glycol monohexyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monoisopropyl ether, tri Propylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, , Tripropylene glycol monobutyl ether, tripropylene glycol monoisobutyl ether, tripropylene glycol monohexyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, propylene A combination of at least one of glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, 3-methoxybutanol, 3-methoxy-3-methyl- .

Examples of the glycol ester compound include methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate , Diethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl Ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, 3-methoxy-3-methyl-1-butylacetate, 3-methoxybutyl acetate Of it can be given alone or in combination of two or more thereof.

Examples of the hydrocarbon-based compound include aliphatic hydrocarbons, aromatic hydrocarbons, naphthenic hydrocarbons, and the like, or a combination of two or more thereof.

As the polar solvent, there may be used one or a combination of two or more of N-methylpyrrolidone,? -Butyrolactone, dimethylsulfoxide, ethylene carbonate, propylene carbonate, and 1,3-dimethyl-2-imidazolidinone .

(2) Amount

The blending amount of the dispersion medium is preferably in the range of 5 to 30 parts by weight based on 100 parts by weight of silver particles.

The reason for this is that by adjusting the compounding amount of the dispersion medium, an appropriate viscosity can be imparted to the conductive paste while stably maintaining the sinterability of the silver particles in the conductive paste.

That is, when the blending amount of the dispersion medium is less than 5 parts by weight, it is difficult to make the paste since the liquid component is small. On the other hand, when the blending amount of the dispersion medium exceeds 30 parts by weight, it is difficult to remove the dispersion medium in the sintering treatment, and the specific resistance may excessively increase.

Therefore, the blending amount of the dispersion medium is more preferably in the range of 6 to 20 parts by weight, and more preferably in the range of 7 to 10 parts by weight, with respect to 100 parts by weight of silver particles.

3. Organic compounds

In forming the conductive paste of the present invention, it is also preferable to blend an organic compound.

This is because the stability with time of the sintered silver particles can be improved by stably maintaining the sinterability of the silver particles in the conductive paste by blending the organic compound.

(1) Type

The type of the organic compound for controlling the sintering property of the particles is not particularly limited, and examples thereof include epoxy resin, phenol resin, polyimide resin, acrylic resin, urethane resin, silicone resin and unsaturated polyester resin A thermosetting resin such as a resin, a vinyl ester resin, a melamine resin and a urea resin, a nitrogen-containing compound such as polyvinylpyrrolidone, triethanolamine and choline, and an organic acid such as ascorbic acid, myristic acid and glutaric acid Or a combination of two or more of them.

Of these, thermosetting epoxy resins or phenolic resins are more preferable organic compounds.

The reason for this is that the use of such thermosetting organic compounds can further improve the stability with time of the sintered silver particles while maintaining the sinterability of the silver particles in the conductive paste more stably.

(2) Amount

The blending amount of the organic compound is preferably set to a value within a range of 0.5 to 10 parts by weight with respect to 100 parts by weight of silver particles.

The reason for this is that by adjusting the compounding amount of the organic compound, the stability with time of the sintered silver particles can be further improved while maintaining the sinterability of the silver particles in the conductive paste stably.

That is, when the blending amount of the organic compound is less than 0.5 part by weight, the durability of the durability thermal conductivity after the sintering treatment may be excessively lowered. On the other hand, when the blending amount of the organic compound exceeds 10 parts by weight, the electric conductivity after the sintering treatment is lowered, and the specific resistance may excessively increase.

Therefore, the blending amount of the organic compound is more preferably in the range of 1 to 8 parts by weight, more preferably in the range of 2 to 5 parts by weight, based on 100 parts by weight of the silver particles.

Here, the relationship between the compounding of the organic compound and the durability of heat conduction will be described with reference to Fig.

That is, Fig. 5 shows the number of cooling / heating cycles (times) when the durability and thermal conductivity of the conductive paste sintered on the abscissa axis is evaluated, and the temperature of the thermocouple sandwiching the measurement sample containing the conductive paste sintered (° C) when the temperature reaches a predetermined temperature.

More specifically, when 1 part by weight of an epoxy resin was blended (characteristic curve B), 2 parts by weight of an epoxy resin was blended with 100 parts by weight of silver particles (Characteristic curve C), 2 parts by weight of phenolic resin (characteristic curve D), and 2 parts by weight of polyimide resin (characteristic curve E), respectively.

The lower the temperature difference of the vertical axis, the better the durability and thermal conductivity of the sintered conductive paste.

A specific evaluation method of such endurance thermal conductivity will be described in Examples.

First, when the organic compound is not blended (characteristic curve A), the predetermined thermal conductivity can be maintained until the number of the cooling / heating cycles is 200, but at the time when the number of cooling / heating cycles is 500, sintering causes cracking , It is understood that the thermal conductivity is completely lost.

On the other hand, when 1 part by weight of the epoxy resin is blended (characteristic curve B), it can be seen that the predetermined thermal conductivity can be maintained until the number of cycles of cooling and heating is 500 and the durability of thermal conductivity is drastically improved.

However, in this case, it can be seen that the thermal conductivity is completely lost when the number of thermal cycles is 1,000.

From this point, it is found that when the epoxy resin is blended in an amount of 2 parts by weight (characteristic curve C) and when the phenol resin is blended in 2 parts by weight (characteristic curve D), a predetermined thermal conductivity can be maintained And the durability thermal conductivity is remarkably improved.

In the case of mixing 2 parts by weight of the polyimide resin (characteristic curve E), the thermal conductivity can be maintained until the number of cycles of cooling and heating is 1,000, but the thermal conductivity is slightly lowered due to the gradual deterioration of the particles The discard can be seen.

Therefore, from the characteristic curve shown in Fig. 5, it is preferable to use an epoxy resin and a phenol resin as the organic compound in order to obtain excellent durability and thermal conductivity. The amount thereof is preferably 0.5 to 10 wt% It is understood that it is desirable to set the value within the negative range.

The relationship between the combination of the organic compound and the resistivity will be described with reference to Fig.

That is, in FIG. 6, the abundance of the organic compound in 100 parts by weight of the silver particles is taken on the abscissa, and the ordinate of the abscissa shows the characteristic curve in which the resistivity (? 占 에) of the electroconductive paste after sintering is taken.

More specifically, a characteristic curve is shown as an organic compound when an epoxy resin (characteristic curve A), an epoxy novolak resin (a kind of epoxy resin) (characteristic curve B) and a phenol resin (characteristic curve C) are used.

As understood from these characteristic curves, the increase in specific resistance can be suppressed to about 2 x 10 < ^-5 > OMEGA. Cm or less even when the epoxy resin and the phenol resin are blended in an amount of 10 parts by weight per 100 parts by weight of the silver particles , And 2 parts by weight, it is understood that it does not contribute to the increase of the resistivity as compared with the case where the composition is not blended.

4. Additives

It is also preferable to add various additives such as an antioxidant, an ultraviolet absorber, a metal ion capturing agent, a viscosity adjuster, an inorganic filler, an organic filler, a carbon fiber, a colorant and a coupling agent to the conductive paste.

Particularly, in general, the conductive paste accelerates the oxidative deterioration due to the addition of the silver particles, and therefore, the antioxidant such as an amine antioxidant, a phenol antioxidant, or a phosphoric acid ester antioxidant, By weight, preferably 0.1 to 10% by weight.

In addition, it is preferable to add silica particles to the conductive paste, and hydrophobic silica or hydrophilic silica can be suitably mixed.

The amount of the silica particles to be added is preferably in the range of 0.1 to 5 wt% with respect to the total amount.

The reason is that if the amount of the silica particles added is less than 0.1% by weight, the effect of addition may not be exhibited. On the other hand, if the added amount of the silica particles exceeds 5% by weight, the electrical conductivity and the thermal conductivity may be excessively lowered.

Therefore, the amount of the silica particles to be added is more preferably in the range of 0.2 to 3 wt%, more preferably in the range of 0.5 to 2 wt% with respect to the total amount.

5. Viscosity

The viscosity of the conductive paste (measurement temperature: 25 ° C) is preferably set to a value within a range of 1,000 to 300,000 mPa · sec.

The reason for this is that when the viscosity of such a conductive paste is less than 1,000 mPa · sec, silver particles tend to precipitate, and electrical conductivity and thermal conductivity may remarkably decrease. On the other hand, when the viscosity of such a conductive paste exceeds 300,000 mPa · sec, handling becomes difficult and it may become difficult to uniformly coat the conductive paste.

Therefore, the viscosity of the conductive paste (measurement temperature: 25 ° C) is more preferably in the range of 3,000 to 100,000 mPa · sec, and more preferably in the range of 10,000 to 80,000 mPa · sec.

6. Density

It is also preferable to set the density of the conductive paste to a value within the range of 1.4 to 7 g / cm 3.

The reason for this is that when the density of the conductive paste is less than 1.4 g / cm 3, the electrical conductivity and the thermal conductivity may remarkably decrease.

On the other hand, when the density of the conductive paste is more than 7 g / cm 3, the handling property may be lowered, or the conductive paste tends to peel off from the adherend.

Therefore, the density of the conductive paste is more preferably in the range of 3 to 6.5 g / cm 3, more preferably in the range of 4 to 6 g / cm 3.

7. Manufacturing Method

The conductive paste is produced by mixing and dispersing a predetermined amount of silver particles in an organic compound or a dispersion medium using, for example, a propeller mixer, a planetary mixer, three rolls, a kneader, And the like.

After uniformly mixing them, it is preferable to filter and remove agglomerates or dusts of silver particles using a filter or the like.

This is because when the conductive paste is applied using a dispenser or the like by filtering the agglomerated particles of silver particles or the like, clogging can be effectively prevented.

When silver particles are used, the silver particles have a cavity therein and a predetermined surface treatment is carried out. As a result, aggregation is less likely to occur. For example, a mesh filter having an opening of 20 to 200 탆 can be easily used There is an advantage that the filtration can be performed.

[Second Embodiment]

The second embodiment is characterized in that the sinterable conductive material contains silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 and a dispersion medium for forming a paste, Of the peak of 2? = 38 占 占 占 at 2? = 38 占 in the X-ray diffraction chart obtained by XRD analysis after sintering treatment of silver particles (250 占 폚, 60 minutes) A step of applying a conductive paste having a value of S2 / S1 within a range of 0.2 to 0.8 when a total intensity of a peak of 占 0.2 占 is S2 to a predetermined position on a substrate for mounting a semiconductor element; , And heating at a temperature of 200 to 450 캜 to sinter the silver particles, thereby mounting the semiconductor element on the substrate.

Hereinafter, the die bonding method using the conductive paste according to the second embodiment will be described in detail for each constituent requirement.

1. First step

(1) Conductive paste

Since the conductive paste can have the same contents as those described in the first embodiment, the description thereof is omitted here.

(2) Semiconductor device / substrate

The adherend to which the conductive paste is applied is a substrate on which a circuit for mounting semiconductor elements is formed.

Therefore, more specifically, a ceramic substrate, a glass substrate, an epoxy resin substrate, a paper / phenol substrate or the like on which a circuit is formed becomes an adherend.

However, in some applications, a conductive paste may be applied to the semiconductor element side.

(3) Application conditions

The coating conditions are not particularly limited. However, it is preferable to apply the coating solution in a range of usually 1 to 500 mu m in thickness using screen printing, inkjet printing, dispenser printing, spin coating printing or the like, , More preferably within a range of 30 to 200 mu m in thickness.

2. Second Step

(1) heating temperature

And the heating temperature in the second step is set to a value within a range of 200 to 450 占 폚.

The reason is that if the heating temperature is less than 200 ° C, the sinterability of the silver particles is remarkably lowered.

On the other hand, if the heating temperature exceeds 450 ° C, the silver particles become excessively sintered and cracks tend to occur.

Therefore, the heating temperature in the second step is more preferably in the range of 230 to 430 占 폚, and more preferably in the range of 250 to 400 占 폚.

The heating apparatus for maintaining the heating temperature is not particularly limited, but a hot air circulating oven, an infrared heating apparatus, an inert gas heating apparatus, a reflow apparatus, or the like is preferably used.

(2) Heating time

The heating time in the second step is preferably in the range of 10 to 180 minutes, though it depends on the heating temperature.

The reason is that if the heating time is less than 10 minutes, the sinterability of the silver particles may remarkably decrease.

On the other hand, if the heating time exceeds 180 minutes, the production efficiency may be excessively lowered, the silver particles may excessively sinter, and cracks tend to occur.

Therefore, the heating time in the second step is preferably within the range of 20 to 120 minutes, more preferably within the range of 30 to 60 minutes.

(3) Pressurizing conditions

In carrying out the second step, the substrate may be connected to the substrate by a non-pressurized state, that is, the self-weight of the semiconductor element, with the conductive paste interposed therebetween. Usually, the pressing condition is set in the range of 5 to 80 kgf / Is preferably set to a value within the range.

The reason is that when the pressing condition is less than 5 kgf / cm 2, the sinterability of the silver particles may remarkably decrease. On the other hand, if the pressing condition exceeds 80 kgf / cm 2, the semiconductor element may be damaged, the silver particles may be excessively sintered, and cracks may easily occur.

Therefore, it is preferable to set the pressing condition in the second step to a value within a range of 10 to 50 kgf / cm 2, more preferably to a value within a range of 20 to 40 kgf / cm 2.

[Example]

Hereinafter, the conductive paste and the like of the present invention will be described in more detail with reference to examples.

[Example 1]

1. Preparation of silver particles

Silver particles were prepared by the liquid reduction method.

Namely, 12 g of silver nitrate was dissolved in 1 kg of ion-exchanged water and 40 g of 25% aqueous ammonia was added to obtain an aqueous solution of ammonium salt of silver.

Next, 1.7 g of sodium hydroxide was added to and dissolved in the aqueous solution of ammonium salt of the obtained silver, and 60 g of 37% formalin was added thereto with stirring to precipitate silver particles.

Next, the obtained silver particles were washed with water, subjected to IPA after filtration.

Next, a surface treatment agent prepared by dissolving 0.3 g of stearic acid in 10 g of IPA was added to perform surface treatment of silver particles, followed by vacuum drying at 100 캜 to obtain spherical hollow particles having a volume average particle diameter of 1.9 탆.

The carbon content in the obtained hollow particles was 0.79% by weight based on 100% by weight of the whole hollow particles obtained.

2. Evaluation of silver particles

(1) XRD analysis

(1) -1 Before sintering treatment

XRD analysis of the silver particles before the sintering treatment was carried out.

That is, the obtained silver particles were filled in a sample holder of an X-ray diffractometer (RINT2500VHF, manufactured by Rigaku Denki K.K.), and the peak height, half width, and integrated intensity at 2θ = 38 ° ± 0.2 ° And crystallite size were measured. The obtained results are shown in Table 1, and the obtained XRD spectrum chart is shown in Fig. 1 (a).

X-ray: Cu / 40 kV / 50 mA

Scan speed: 4 deg / min

Sampling width: 0.02 deg

Scanning range: 20 to 90 degrees

(1) -2 After sintering treatment

XRD analysis of silver particles after the sintering treatment was carried out.

The silver particles thus obtained were sieved in a 100 mesh sieve so as not to overlap with each other on the glass plate surface and sintered by heating in a circulating air dryer at 250 캜 for 60 minutes to obtain silver particles after sintering , XRD analysis was carried out under the same conditions as before the sintering treatment. The obtained results are shown in Table 1, and the obtained XRD spectrum chart is shown in Fig. 1 (b).

The peak height ratio (L2 / L1), the half width ratio (W2 / W1) and the integral intensity ratio (S2 / S1) were calculated based on the XRD analysis results before and after the sintering treatment. The obtained results are shown in Table 1.

3. Preparation of conductive paste

100 parts by weight of the obtained silver particles and 10 parts by weight of dipropylene glycol monomethyl ether acetate (DPMA) as a dispersion medium were accommodated in a container equipped with a stirrer, followed by uniform mixing using a stirring device.

Next, a filtration process was performed using a filtration apparatus equipped with a mesh filter having an opening of 63 탆 to obtain the conductive paste of Example 1.

4. Evaluation of conductive paste

(1) Sinterability

The sinterability of the obtained conductive paste was evaluated.

That is, the obtained conductive paste was applied on a silver plated copper substrate of 8 mm x 12 mm x 2 mm so as to have a thickness of 25 m, and then a silver-plated silicon semiconductor device of 3 mm x 4 mm x 0.4 mm Respectively.

Next, the conductive paste was sintered in a breeze oven under the conditions of no pressure, temperature of 250 DEG C for 1 hour, and then sintered to a room temperature to obtain a measurement sample.

Next, the cut section of the obtained sintered product was observed under a microscope, and the sinterability was evaluated according to the following criteria. The obtained results are shown in Table 1.

⊚: silver particles are uniformly sintered, and no sintered portion is seen at all

○: The silver particles are almost uniformly sintered and the sintered portion is hardly visible

DELTA: Silver particles were partially sintered, but the unsintered portion was not observed.

X: silver particles do not sinter and most of the sintered portion is sintered

(2) Resistivity (electrical conductivity)

The electrical conductivity of the obtained conductive paste was evaluated.

That is, the obtained conductive paste was printed on a prepalative glass plate in a line of 50 mm x 1 mm x 0.1 mm, and the conductive paste was sintered in a breeze oven by heating under the conditions of no pressurization and temperature of 250 DEG C for 1 hour, The measurement was made as a sample.

Next, the resistance value (number of measurement: 3) between two points (20 mm) was measured by a four-terminal method (measuring current: 0.1 mA) using a four-terminal tester and the average value thereof was calculated, And evaluated according to the following criteria. The obtained results are shown in Table 1.

?: The average value of the resistivity is a value less than 5 占^10-6 ? 占. M.

?: The average value of the resistivity is a value of 5 占^10-6 ? 占 ㎝ m and not more than 5 占^10-5 ? 占. M.

?: Average value of resistivity is a value of 5 占^10-5 ? 占 ㎝ m and less than 5 占^10-3 ? 占 m.

X: Average value of resistivity is 5 x 10 < ^-3 >

[Example 2]

In Example 2, silver particles and an electroconductive paste were prepared in the same manner as in Example 1 except that spherical hollow silver particles having a volume average particle diameter of 2.3 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 7 (a) to 7 (b), respectively.

[Example 3]

In Example 3, silver particles and a conductive paste were produced in the same manner as in Example 1, except that spherical hollow particles having a volume average particle diameter of 1.6 占 퐉 were obtained by controlling the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 8 (a) to 8 (b), respectively.

The carbon content of the resultant hollow particles was 0.82% by weight based on 100% by weight of the whole hollow particles obtained.

[Example 4]

In Example 4, silver particles and a conductive paste were prepared in the same manner as in Example 1 except that spherical hollow silver particles having a volume average particle diameter of 2.4 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The results obtained are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 9 (a) to 9 (b), respectively.

[Example 5]

In Example 5, silver particles and an electroconductive paste were prepared in the same manner as in Example 1, except that spherical hollow silver particles having a volume average particle diameter of 3.8 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of the silver particles before sintering treatment and after sintering treatment are shown in Figs. 10 (a) to 10 (b), respectively.

[Example 6]

In Example 6, silver particles and an electroconductive paste were prepared in the same manner as in Example 1, except that spherical hollow silver particles having a volume average particle diameter of 5.4 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of the silver particles before and after the sintering treatment are shown in Figs. 11 (a) and 11 (b), respectively.

[Example 7]

In Example 7, silver particles and an electroconductive paste were prepared in the same manner as in Example 1, except that spherical hollow silver particles having a volume average particle diameter of 3.0 占 퐉 were obtained by controlling the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 12 (a) to 12 (b), respectively.

[Example 8]

In Example 8, silver particles and an electroconductive paste were prepared in the same manner as in Example 1, except that spherical hollow silver particles having a volume average particle diameter of 4.0 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 13 (a) to 13 (b), respectively.

[Example 9]

In Example 9, silver particles and an electroconductive paste were prepared in the same manner as in Example 1 except that spherical hollow silver particles having a volume average particle diameter of 4.5 占 퐉 were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 14 (a) to 14 (b), respectively.

[Example 10]

In Example 10, silver particles and an electroconductive paste were prepared in the same manner as in Example 1 except that spherical hollow silver particles having a volume average particle diameter of 2.9 mu m were obtained by adjusting the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The results obtained are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 15 (a) to 15 (b), respectively.

[Example 11]

In Example 11, silver particles were obtained in the same manner as in Example 1 except that the particles of the flaky solid particles having a volume average particle diameter of 3.8 mu m were controlled by controlling the conditions for preparing the silver particles by the liquid phase reduction method, Were prepared and evaluated. The obtained results are shown in Table 1, and XRD spectrum charts of the silver particles before sintering treatment and after sintering treatment are shown in Figs. 16 (a) to 16 (b), respectively.

[Comparative Example 1]

In Comparative Example 1, silver particles were prepared by the atomization method, and silver particles and a conductive paste were produced and evaluated in the same manner as in Example 1, except that spherical solid silver particles having a volume average particle diameter of 5.0 占 퐉 were obtained. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 17 (a) to (b), respectively.

As the atomization method, a water atomization method (see Japanese Patent Application Laid-Open No. 11-106804) was used in which silver particles were produced by pulverizing molten metal and rapidly solidifying and solidifying rapidly by using high-pressure water.

[Comparative Example 2]

In Comparative Example 2, silver particles and an electroconductive paste were prepared in the same manner as in Example 1, except that hollow fine silver particles having a volume average particle size of 3.0 占 퐉 were obtained by controlling the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of the silver particles before and after the sintering treatment are shown in Figs. 18 (a) and (b), respectively.

[Comparative Example 3]

In Comparative Example 3, silver particles and a conductive paste were produced in the same manner as in Example 1, except that spherical solid silver particles having a volume average particle diameter of 1.8 占 퐉 were obtained by controlling the conditions for preparing silver particles by the liquid phase reduction method, I appreciated. The obtained results are shown in Table 1, and XRD spectrum charts of the silver particles before sintering treatment and after sintering treatment are shown in Figs. 19 (a) and (b), respectively.

[Comparative Example 4]

In Comparative Example 4, silver particles and a conductive paste were prepared and evaluated in the same manner as in Example 1, except that spherical solid particles having a volume average particle diameter of 7.7 占 퐉 were obtained by preparing silver particles by atomization. The obtained results are shown in Table 1, and XRD spectrum charts of silver particles before sintering treatment and after sintering treatment are shown in Figs. 20 (a) to 20 (b), respectively.

[Table 1]

[Example 12]

1. Preparation of conductive paste

In Example 12, silver paste was prepared in the same manner as in Example 1, except that 10 parts by weight of N-methylpyrrolidone (NMP) was added to 100 parts by weight of silver particles obtained at the time of producing the conductive paste instead of DPMA as a dispersion medium. To prepare a conductive paste.

2. Evaluation of conductive paste

(1) initial thermal conductivity

The initial thermal conductivity of the obtained conductive paste was evaluated.

That is, the obtained conductive paste was applied on a silver plated copper substrate of 8 mm x 12 mm x 2 mm so as to have a thickness of 25 m, and then a silver-plated silicon semiconductor element of 3 mm x 4 mm x 0.4 mm was placed thereon .

Next, the conductive paste was sintered in a breeze oven under the conditions of no pressure, temperature of 250 DEG C for 1 hour, and then sintered to a room temperature to obtain a measurement sample.

Next, both surfaces of the measurement sample thus obtained were sandwiched by copper tips for fixing thermocouples, then the copper tips on the side of the silver plated copper substrate were placed on the heat dissipation block, and on the copper tips on the silver plated silicon semiconductor element side I installed a heater.

Next, the heater was activated to heat the measurement sample, and the temperature difference (measured number: 3) when the temperature difference of the upper and lower thermocouples reached the equilibrium was measured, and the average value was calculated and evaluated according to the following criteria. The obtained results are shown in Table 2.

&Amp; cir &: The temperature difference in equilibrium in the thermocouple is less than 50 DEG C

A: The temperature difference at the time of equilibrium in the thermocouple is not less than 50 캜 and less than 55 캜

?: Temperature difference at equilibrium in a thermocouple is 55 占 폚 or more and less than 60 占 폚

X: The temperature difference at the time of equilibrium in the thermocouple is 60 DEG C or more

(2) Durability thermal conductivity

The durability and thermal conductivity of the obtained conductive paste was evaluated.

That is, the measurement sample obtained in the same manner as in the evaluation of the initial thermal conductivity was cooled in a breeze oven under the conditions of no pressurization, temperature -55 DEG C, and 15 minutes, and then heated under no pressure and at a temperature of 150 DEG C for 15 minutes Exposed to a cooling / heating cycle, measurement samples were taken out every 200 cycles, 500 cycles, and 1000 cycles, and the temperature difference at the time of equilibrium in the thermocouple was measured and evaluated. The obtained results are shown in Table 2.

[Example 13]

In Example 13, 9 parts by weight of DPMA as a dispersion medium, 1.0 part by weight of an epoxy resin (Ep 49-25, manufactured by ADEKA Corporation) as an organic compound and 100 parts by weight of a curing agent (Manufactured by Shikoku Chemical Industry Co., Ltd., C17Z) were added, and silver particles and a conductive paste were prepared and evaluated in the same manner as in Example 12. [ The obtained results are shown in Table 2.

[Example 14]

In Example 14, 8 parts by weight of DPMA was used as a dispersion medium, 2.0 parts by weight of an epoxy resin (Ep 49-25, manufactured by ADEKA Corporation) as an organic compound, 100 parts by weight of a curing agent (Manufactured by Shikoku Chemical Industry Co., Ltd., C17Z) were added, and silver particles and a conductive paste were prepared and evaluated in the same manner as in Example 12. The obtained results are shown in Table 2.

[Example 15]

In Example 15, 5.6 parts by weight of DPMA was used as a dispersion medium, 100 parts by weight of a phenolic resin (Regisol PL-5208, manufactured by Sigma-Aldrich Corp.) as an organic compound, Silver particles and a conductive paste were prepared and evaluated in the same manner as in Example 12, The obtained results are shown in Table 2.

[Example 16]

In Example 16, 8.1 parts by weight of NMP as a dispersion medium, 2.0 parts by weight of a polyimide resin (BANI-X made by Maruzen Sekiyu Kagaku Co., Ltd.) 2.0 And 0.1 part by weight of an epoxy resin (Epiclon 7050, manufactured by DIC Corporation) as an additive were compounded, and silver particles and a conductive paste were prepared and evaluated in the same manner as in Example 12. [ The obtained results are shown in Table 2.

[Table 2]

INDUSTRIAL APPLICABILITY As described above, according to the conductive paste of the present invention, as the sinterable conductive material, silver particles of a predetermined particle size having a predetermined crystal change characteristic specified by XRD analysis are used and a dispersion medium for paste- , The sinterability of the silver particles can be easily controlled without depending on the crystallinity of the silver particles before the sintering treatment, and further, the excellent electrical conductivity and thermal conductivity can be stably obtained after the sintering treatment.

Therefore, the conductive paste of the present invention is expected to be widely used as a substitute for high-temperature solder since it can be used as a die bonding material particularly for use in heat radiation bonding between a semiconductor element and a substrate.

Claims (10)

As a conductive paste containing silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material and a dispersion medium for forming a paste,
The integral intensity of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is represented by S1,
When the integral intensity of the peak at 2? = 38 占 占 占 is 2 in the X-ray diffraction chart obtained by XRD analysis after sintering the silver particles (250 占 폚, 60 minutes)
And the value of S2 / S1 is set to a value within a range of 0.2 to 0.8. The method according to claim 1,
When the peak height of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is L1,
When the peak height of the peak at 2? = 38 占 0.2 占 in the X-ray diffraction chart obtained by XRD analysis after sintering the silver particles (250 占 폚, 60 minutes) is L2,
And the value of L2 / L1 is set to a value within a range of 0.5 to 1.5. 3. The method according to claim 1 or 2,
The half width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis before the sintering treatment of the silver particles is defined as W1,
When the half-width of the peak at 2? = 38 占 占 占 in the X-ray diffraction chart obtained by XRD analysis after sintering the silver particles (250 占 폚, 60 minutes) is W2,
And the value of W2 / W1 is set to a value within the range of 0.3 to 0.9. 4. The method according to any one of claims 1 to 3,
Wherein the silver particles are hollow particles, and the hollow particles are particles. 5. The method according to any one of claims 1 to 4,
Wherein the surface of the silver particles is covered with an organic surface treatment agent comprising at least one selected from an organic acid, an organic acid salt, a surfactant and a coupling agent. 6. The method according to any one of claims 1 to 5,
Wherein the mixing amount of the dispersion medium is within a range of 5 to 30 parts by weight based on 100 parts by weight of the silver particles. 7. The method according to any one of claims 1 to 6,
Wherein the dispersion medium is at least one compound selected from the group consisting of a glycol ether compound, a glycol ester compound, a hydrocarbon compound and a polar solvent. 8. The method according to any one of claims 1 to 7,
Further comprising an organic compound and adjusting the amount of the organic compound to be in a range of 0.5 to 10 parts by weight based on 100 parts by weight of the silver particles. 9. The method according to any one of claims 1 to 8,
Wherein the organic compound is a thermosetting resin containing at least one of an epoxy resin and a phenol resin. And a dispersion medium for forming a paste, wherein the silver particles having a volume average particle diameter of 0.1 to 30 占 퐉 as a sinterable conductive material and a dispersion medium for forming a paste, And the integral intensity of the peak at 38 占 占 占 is S1, and the integral intensity of the peak at 38 占 0.2 占 in the X-ray diffraction chart obtained by XRD analysis after the sintering treatment (250 占 폚, 60 minutes) Applying a conductive paste having a value of S2 / S1 within a range of 0.2 to 0.8 when the integrated intensity of the peak is S2, to a predetermined position on the substrate for mounting the semiconductor element;
Heating at a temperature of 200 to 450 캜 to sinter the silver particles to mount the semiconductor element on the substrate
The die bonding method comprising:

Images